Method of preparation of material for neutron bombardment



Feb. 3, 1959 c. L. URA El'AL METHOD OF PREPARATION OF MATERIAL FOR NEUTRON BOMBARDMENT Filed March 31, 1947 INVENTORS Cheszer L. Ur'a, Oscar- Jlisman, &

METHGD F PREPARATION OF MATERIAL FOR NEUTRON BGMBARDMENT Chester L. Ura, Hamtramck, Mich, and Oscar Sismau and Robert B. Briggs, Oak Ridge, Tenn., assignors to the United States at America as represented by the United States Atomic Energy Commission Application March 31, 1947, Serial No. 738,390

2 Qlaims. (Cl. 204-4932) This invention relates to the preparation of material for processing in a neutron reactor and is particularly concerned with the preliminary preparation of the material to be bombarded.

In neutronic reactors, that is, in a pile for instance, in which material is to be transmuted, it is conventional that the material to be processed, that is bombarded by neutrons, be in the form of slugs or cartridges readily suited to being put in the reactor for processing and removal therefrom. The slugs or cartridges are desirably cylindrical in form and structurally strong and rigid and usually they are canned, that is, incased in an aluminum container, the container being made of a material not subject to deterioration from the effects of a coolant that may be used in the reactor and not having too great a tendency toward absorbing neutrons.

The material to be bombarded or processed may be in a powder or crystalline form requiring that it be formed and compressed into cylindrically shaped slugs or cartridges before insertion in the reactor. For example, the material to be bombarded may be thorium oxycarbonate, and experience has established that this material, after being compressed into dense, rigid, cylindrically shaped slugs of the proper size to exactly fit into the cans or containers, would crumble when handled, the slug thus being unsatisfactory for normal processing in the reactor. Formation of the slugs in this manner by compression in a die additionally presented the difficulty that the die necessarily had to be cleaned and relubricated after each compression.

The primary object of our invention is to provide a method for overcoming the difliculties set forth in the foregoing, that is to provide a method of forming slugs or cartridges of the material to be bombarded having good structural properties as required and to eliminate the necessity of cleaning and relubricating the die after compression of each cartridge.

More specifically the object of the invention is to provide a method of forming slugs or cartridges of material to be processed in a neutronic reactor, for example, by incasing the powdered material first in a material, such as aluminum foil, and then compressing the powder under relatively high pressure within its foil envelope to produce a dense, rigid billet, or cartridge, suitable for processing.

Further objects and numerous of the advantages of our invention will become apparent from the following detailed description and annexed drawing, Fig. 1 of which is a schematic showing of a die block having a charge of powdered material incased in foil therein preliminary to being compressed into the desired form. Fig. 2 is a slug or cartridge of the material within its envelope after compression into a dense, rigid cylindrical form.

In practicing our invention, the material to be processed, for example, thorium oxycarbonate, is placed within a tube formed of a material such as aluminum foil, that is, the aluminum foil is rolled into tube form of the proper size to fit into the die, and a weighed portion of 2,872,402 Patented Feb. 3, 1959 thorium oxycarbonate is placed in the tube, the ends of which are crimped or folded over, as may be seen on Fig. 1 of the drawing, the tube being designated by numeral 3. The tube containing the material is then placed in the die, indicated at 1 on the drawing, which is cylindrical in form and of the size of the slug or cartridge desired. The material incased in its foil wrapper or envelope is then compressed in the die by means of the pressure ram schematically indicated at 2, which fits into the die like a piston, the material and its wrapper then being compressed under a pressure of 25 tons. The pressure exerted upon the material compresses it into a structurally strong, dense, and rigid slug or cartridge. The foil envelope, of course, remains in place and the ends of the incasing envelope are compressed flat by the force of compression. As a result of this process, cartridges of material are produced which are in the desired form and possess the desired characteristics adapting them for handling in the manner intended, that is, incasement in the slug cans, their size being such as to leave a minimum of free air space in the cans, and subsequent insertion in the reactor and removal therefrom. The process eliminates the need of cleaning and relubricating the die after each compression, and difficulties involved in preparation for handling of the material are reduced to a minimum.

It will be understood that our invention may be practiced in various forms and manners and it is intended, therefore, that the following claims be interpreted in an illustrative rather than a limiting sense.

We claim:

1. In the preparation of material for irradiation in a neutronic reactor, said material being originally in comminuted form which is not susceptible by itself to the formation of a rigid cartridge by compression, the steps of encasing a large number of particles of the comminuted material in a single metallic foil envelope, compressing said foil-enveloped material under sufficient pressure to form a rigid cartridge and sealing the cartridge in a metallic can.

2. In the preparation of material for irradiation in a neutronic reactor, said material being originally in comminuted form which is not susceptible itself to the formation of a rigid cartridge by compression, the steps of encasing a large number of particles of the comminuted material in a single metallic foil envelope, compressing said foil-enveloped material under a pressure of 25 tons to form a rigid cartridge, and sealing the cartridge in a metallic can.

References Cited in the file of this patent UNITED STATES PATENTS 251,281 Pritchard Dec. 20, 1881 1,406,542 Crocker Feb. 14, 1922 2,206,634 Fermi et al July 2, 1940 2,290,734 Brassert July 21, 1942 FOREIGN PATENTS 114,150 Australia May 2, 1940 114,151 Australia May 3, 1940 861,390 France Feb. 7, 1941 233,011 Switzerland Oct. 2, 1944 OTHER REFERENCES Dunning et al.: Phy. Review, vol. 48, pp. 265-280 (1935).

Business Week, pp. 57-63, Sept. 1, 1945.

A General Account of the Development of Methods of Using Atomic Energy for Military Purposes, H. D. Smyth, Aug. 1945, pp. 26, 106, 107. 

1. IN THE PREPARATION OF MATERIAL FOR IRRADIATION IN A NEUTRONIC REACATOR, SAID MATERIAL BEING ORIGINALLY IN COMMINUTED FORM WHICH IS NIT SUSCEPTIBLE BY ITSELF TO THE FORMATION OF A RIGID CARTRIDGE BY COMPRESION, THE STEPS OF ENCASING A LARGE NUMBER OF PARTICLES OF THE COMMINUTED MATERIAL IN A SINGLE METALLIC FOIL ENVELOPE, COMPRESSING SAID FOIL-ENVELOPED MATERIAL UNDER SUFFICIENT PRESSURE TO FORM A RIGID CARTRIFGE AND SEALING THE CARTRIDGE IN A METALLIC CAN. 